have a peer down the oil filler cap, and try to remove the breather on the same place on the opposite rocker cover (it unscrews)
have a look in there too. if they look like theres a barbecue been poured in there, its gonna need cleaning out, and thats a messy job.
thats said, if it made it to 170K, its probably gonna be alright anyway!
assuming its not losing any water or overheating, a good clean out every so often is all they usually need.